Although paleontologists and evolutionary biologists generally agree that a huge asteroid, striking Earth, wiped out the dinosaurs, (or the non-avian ones), there remains disagreement over whether dinosaurs were in full vigor, or whether they as a class were already in decline before the arrival of the space rock that finished them off.
In a new study published this June in the journal Nature Communications, a team of scientists led by Fabien Condamine makes the case for the already-in-decline view.
That asteroid hit Earth about 66 million years ago. Yet long before that, starting at 10 million years before that impact, the numbers of dinosaur species extinctions were increasing and the rate of the split-off of new species fell. The decline was a consequence of “ecological and environmental issues.” Specifically, dinosaurs relied on warm temperatures but the planet was getting colder.
Condamine is a researcher with the Institut des Sciences de l’Evolution de Montpelier (France).
Strange New Worlds:
On a related subject, the study indicates that there was a rise in the number of mammalian species in the period before the asteroid finished the dinosaurs off.
After that impact, as Condamine puts it: “they [mammals] had their chance to build new kinds of ecosystems which we see today,” rather than simply existing on the fringe of a lizard-centered ecosystem.